1. Postoperative fever Dr. S. Parthasarathy MD, DA, DNB, Dip Diab.MD,DCA, Dip software based statistics, PhD (physiology)

2. What is it ?? Fever is regulated elevation of body temperature, in which a raised central set point---- leads to “ intentional ” increased heat generation through some combination of shivering/muscle contraction, peripheral vasoconstriction, and increased metabolism in brown adipose tissue. Dysregulation, 41 deg. + === hyperthermia

3. Pyrogens in fever Yes Hyperthermia. NO 38 degree or 38.5 degrees a few hours apart in two occasions IL 6 production + Genetic predisposition

4. Incidence 27 to 51 % Upto 90 % in one study if time upto one week in a study Infection < 50 %

5. Causes 1.2. Infectious noninfectious ↓ Surgery related & Non surgery related

6. Surgery related infection Wound infection Intra-abdominal abscess Leaking anastomosis with peritonitis Infected prosthetic material Acute cholecystitis Transfusion-related infection

7. Nonsurgery related Pneumonia Urinary tract infection Infected hematoma Systemic bacteremia Clostridium difficile enterocolitis Pharyngitis, sinusitis But infectious

8. Non infectious Medications (anesthesia or other) Thrombophlebitis Deep vein thrombosis Adrenal insufficiency Malignancy Pulmonary embolus Myocardial infarction Thyrotoxicosis Common

9. Surgical site infection Superficial – easy to diagnose But deep -- ?? Usually after 5 or 6 days But fulminant myonecrosis in the site due to stretococcus or clostridia. Within hours after surgery

10. Periop catheters UTI Fever, bacteriuria – UTI Really the post op fever is due to this ??

11. Pneumonia Intubated long duration COPD Upper abdominal or thoracic surgery Diagnose and treat – ( other causes ) Settings

12. Sinusitis Nasotracheal intubation Long term ryles tube CT sinuses

13. Cholecystitis is occasionally encountered in the postoperative setting, and may be either acalculous or calculous, patients who are older, more debilitated, and/or on prolonged bowel rest. The diagnosis may be challenging to make in patients with recent abdominal surgery USG abdomen

14. Catheter related CVP IA lines Difficult to diagnose Strict asepsis

15. Transfusion - related infections manifesting as febrile illness may be seen after surgery, most commonly caused by cytomegalovirus. Typically, these patients will develop fever after hospital discharge, although they may manifest with cryptic fever as inpatients

16. Infected hematoma Days after surgery Bleed – clot – infect Clinical, USG Infected prosthesis

17. Non infectious

18. Why ?? Tissue damage alone results in the disruption of phospholipids from the cell membrane, leading to a cascade of prostaglandins and cytokines which eventually lead to a body temperature elevation 25 – 50 % day 1 fever

19. Noninfectious Etiologies Antibiotics, antihistamines, barbiturates Myelographin Ketamine (anaes) Amphetamine, methamphetamine Anti epileptic drugs Alcohol and benzodiazepine withdrawal Anticoagulants Atropine Drugs IV solutions

20. DVT and pulmonary embolism major orthopedic procedures involving the lower extremities, oncologic, and trauma surgeries are complicated by significant rates of VTE events, even with appropriate prophylaxis. No need to get infarct to get fever

21. Gout Acute exacerbation of crystal - associated arthropathy, particularly gout, is a reasonably common cause of fever after surgery, but its recognition in this situation is often delayed. Continue anti gout drugs

22. Steroid withdrawal chronic exposure to corticosteroid not continued perioperatively refractory hypotension, fever, abdominal symptoms, and delirium. Correct with steroids

23. Fat embolism The possibility of fat embolism needs to be entertained in the patient who has undergone long bone fracture, correction Fever, respiratory distress, petechial rash, and confusion.

24. Thrombophlebitis Look at the site of venous or arterial cannulations By the side of a venflon – redness and tenderness !!

25. Wind, Water, Wound, Walking Wonder Drugs

26. Wind --------------- Water Atelectasis 24 – 48 hours Pneumonia later UTI Catheter related infections Anastamotic leaks

27. Wound walking Surgical site Necrotizing fascitis Infected prosthesis DVT Embolism Wonder drugs

28. What is when ?? Wind, → Water, → Wound, → Walking → Wonder Drugs → 1-2 days 3-5 days 5-7 days ( 6 hours) 4-5 days After seven days Generally

29. Approach

31. History past medical history, including history of gout, medications and allergies, alcohol and other drug use; details of the surgery itself, receipt of blood products; any complaints of cough, Breathless, chest pain, diarrhea, joint pain, dysuria, flank pain, Allergy,alcohol arthrits Blood Cough chest pain Drugs, dysuria diarhea,dyspnea Details – surgery ABCD

32. Clinical features Vitals CVS,RS, abdomen Skin and wound Alcohol withdrawal may have also sinusitis !!

33. Classification of Fever INTERMITTENT (Spiking) –Intermittent elevation of temp with regular return to normal (infection within closed space-abscess) REMITTENT/FLUCTUATING Continuous type of fever drop in fever without returning to normal-brucellosis, blood stream infections, infected arterial grafts, phlebitis. UNREMITTING/CONTINUOUS Continuous high fever-CNS injury, pneumonias, Note: Hydration, Muscle activity, sleep and medication also alter febrile response.

34. Sometimes – there is something matters AGE; –INFANTS HAVE A HIGH TEMP ranging as high as 40.6 –OLD AGED Patients - DIMNISHED RESPONSE MEDICATIONS- NSAID, Steroids-absence of fever TRAUMA- trauma to hypothalamus disturbs thermoregulatory mechanism. IMMUNOSUPRESSION- Altered production of endogenous leukocyte, pyrogens, lack a febrile response

35. Investigate TC,DC,urine, peripheral smear, chest Xray, All cultures ???? USG, CT etc.. ECG, thyroid Serum procalcitonin – infectious ??

36. Do we need investigations ?? Many a time, the fever comes down normally within one to two weeks. Lab tests are useful ?? Some bacteria results in lab but fever comes from some other cause ??

37. surgery for malignancy, bowel resection, number of febrile days, higher fever and moderately increased white blood cell count. Our lab investigations may be useful.

38. Benign postoperative fever Hypothalamus becomes inhibited by Anesthetic agents –fall in body temp, Once anesthesia effect is gone- recovery of this mechanism intracranial core temp still decreased- thermosenstive receptors in hypothalamus sense decreased temp and attempt to raise body temp to hypothalamic set point, Over compensation with a mild febrile episode in post op period This is diagnosed by exclusion

39. Set point moves up Preop Postop

40. Aims of treatment To reduce the elevated hypothalamic set point To facilitate heat loss To reduce the demand for oxygen (i.e., for every increase of 1°C over 37°C, there is a 13% increase in oxygen consumption) Prevent to aggravate preexisting cardiac, CNS pulmonary disease To prevent seizures in children with a history of febrile illness

41. Prevention Clean shave and preparation Infection risk is reduced by using aseptic technique during catheter insertion with maximal barrier precautions including a mask, cap, sterile gown, and large sterile drape, Less time catheter Orogastric tube Smoke stop, nutrition, preop nasal mupirocin, obesity ??

42. Treatment Antipyretics Antibiotics need ?? Stringent glycemic control Respiratory support Inotropes Surgery

43. Summary When to call ?? Incidence Classification Common causes ?? Wind water wound walk wonder drugs What is when ?? Diagnosis, management